Platt, Robert C
naca-report-558
1937
Report presents the results of drag and pressure tests of spheres having diameters of 2, 4, 6, 8, 10, and 12 inches in eight NACA wind tunnels, in the air ahead of the carriage in the NACA tank, and beneath an autogiro in flight .
An Adobe Acrobat (PDF) file of the entire report:
http://naca.central.cranfield.ac.uk/reports/1937/naca-report-558.pdf